• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.249-254
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• 1998

A control approach for the robust position control of induction motors based on the improved binary disturbance observer is described. The conventional binary disturbance observer is used to remove the chattering problem of a sliding mode disturbance observer. However, the steady state error may be existed in the conventional binary disturbance observer because it estimates external disturbance with a constant boundary layer. In order to overcome this problem, a new binary disturbance observer with an integral augmented switching hyperplane is improved. The robustness is achieved, and the continuous control is realised by employing the improved observer without the chattering problem and the steady state error. The effectiveness of the improved observer is confirmed by the comparative experimental results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.104-110
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• 2015

This paper describes a power quality disturbance generator for the test of a microgrid. The generator provides phase-angle jump as well as voltage sag with simple structure. The main components of the generator are SCR thyristors and transformers, therefore, high reliability and high efficiency can be obtained without switching losses. The operating principle of the proposed scheme is described and the voltage and current characteristics in case of voltage sag with phase-angle jump is analyzed. The usefulness of the proposed topology is verified through simulations and experimental results.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.830-835
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• 1998

This paper describes a new digital control method of 3-phase PWM inverter with LC filter for uninterruptible power supply(UPS). The overall control system is based on the dead beat control, which has the minor loop of current control within the voltage control major loop. In this paper, the full-order disturbance observer is proposed to compensate the disturbances generated due to a sudden change of load currents. The proposed disturbance observer is composed of dead beat observer which estimates state values within a finite time, and cancels the disturbances by adding feedforward compensation loop in the control system. In addition, on order to remove a defect of oscillation generated in output of conventional dead beat controller, a modified dead beat algorithm is proposed in this paper.

• Proceedings of the KIEE Conference
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• summer
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• pp.1254-1256
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• 2004

This paper deals with a novel 3-phase power quality disturbance generator. The proposed generator can be applied to the performance that of custom power devices. Voltage sag, swell and outage are provided by the generator. The control scheme for the disturbance generation is simple, and hardware setup is cost effective, compared with conventional scheme. The operating principle of the generator is described and the usefulness verified through simulation with 10KVA power rating.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.69-71
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• 2008

Recently, the interest on power quality has been hot issue because the equipments cause voltage disturbance and become more sensitive to the voltage disturbance. The DVR(Dynamic Voltage Restorer) is one of the Custom Power Device that can compensate the voltage. DVR operates as a series connected compensator whose output voltage can be controlled system voltage. And the magnitude of compensation voltage is limited by the characteristics of system and load. Compensation capability of DVR was simulated by EMTDC under several condition. This paper analyzed effect of DVR's compensation at power quality test center which has SSFG(Sag, swell, and Flicker Generator, CPDs(SSTS, DVR, DSTATCOM), and loads.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.705-715
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• 2007

Recently, the interest on power quality has been hot issue because the equipments cause voltage disturbance and have become more sensitive to the voltage disturbance. Additionally, the reseach on power electronic equipments applying to the high power has been increased. This paper deals with Line-Interactive Dynamic Voltage Restorer(LIDVR) system using 7-Level H-Bridge inverter, which is one of the solutions to compensate the voltage disturbance and to increase the power of equipments. The LIDVR has the following advantages comparing to the DVR with the series injection transformer. It has the power factor near to unity under the condition of normal source voltage, can compensate the harmonic current of the load and the instant interruption, and has the fast response. First, the construction, the operation mode and algebraic modeling of LIDVR are reviewed. And then the voltage control algorithm is proposed to get the sinusoidal load voltage with constant amplitude. Finally, simulation and experiment results verify the proposed LIDVR system.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1195-1199
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• 1998

In this paper a design method of robust power system stabilizers is proposed by means of robust linear quadratic regulator design technique under power system's operating condition change, which is caused by inner structure uncertainties and disturbances into a power system. It is assumed that the uncertainties present in the system are modeled as one equivalent signal. In this connections an optimal LQR control input for disturbance rejection, the output feedback gain for eliminating the disturbance are calculated. In this case. PSS input signal is obtained on the basis of weighted ${\Delta}P_e$ and $\Delta\omega$. In order to stabilize the overall control of system. Pole placement algorithm is applied in addition. making the poles of the closed loop system to move into a stable region in the complex plane. Some simulations have been conducted to verify the feasibility of the proposed control method on a machine to infinite bus power system. From the simulation results validation of the proposed method could be achieved by comparisons with the conventional PSS with phase lag-lead compensation.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.499-503
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• 2009

In this study, the dynamic characteristic of a contact wire and pantograph suppling electrical power to high-speed trains are investigated from an electrical response point of view. To analysis power line disturbance by induced contact loss phenomenon for high speed operation, a hardware Simulator which considered contact loss between contact wire and the pantograph as well as contact wire deviation is developed. It is confirmed that a contact wire and pantograph model are necessary for studying the dynamic behavior of the pantograph system. One of the most important needs accompanied by increasing the speed of high-speed train is reduced that an arc phenomenon by loss of contact brings out EMI. In case of a high-speed train using electrical power, as comparison with diesel rolling stock, PLD(Power Line Disturbance) such as harmonic, transient voltage and current, EMI, dummy signal injection etc usually occurs. Throughout experiment, it is verified that an arc phenomenon is brought out for simulator operation and consequently conducted noise is flowed in electric circuit by power line disturbance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.353-356
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• 1997

Hydraulically driven manipulators are superior to electrically driven ones in the power density and electrical insulation. But an electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and this parameter fluctuations are greater than those of electrically driven manipulator. So this is relatively difficult to realize not only stable contact work but also accurate force control for the autonomous field task such as the maintenance task of high voltage active electric line or the automatic excavation task by hydraulic excavator. In this report, we propose robust force control algorithm, which can be applied to there real field task such as the construction field, nuclear plant and so on. Proposed force controller has the same structure as that of disturbance observe for position control. The difference between force and position disturbance observer is that the input and output of disturbance observer are forces in the case force disturbance observer and the plant varies much compared to the case of position control. In the design of force disturbance observer, generalized plant is derived and the stabilized filter is designed by H infinity control theory to ensure the robuts t stability even though the stiffness of environment changes from sponge to steel, and the contact surface also changes from flat to round shape. Experimental results show that highly robust force tracking by a 6-link electro-hydraulic manipulator could be achieved under various environment conditions.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.372-378
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• 2012

This paper deals with a 3-phase voltage disturbance generator for a performance test of custom power devices such as dynamic voltage restorers (DVR), dynamic uninterruptable power supplies (UPS), etc. The operating principle of the proposed circuit is described in each mode of voltage sag, swell, outage, and unbalance. The main components of the proposed disturbance generator are silicone controlled rectifier (SCR) thyristors, variable autotransformers, and transformers. Therefore, the disturbance generator can be implemented with a considerably low cost compared to the conventional pulse width modified (PWM) inverter and converter type generators. Furthermore, it has good features of high reliability with simple structure, high efficiency caused by no PWM switching of the SCR thyristors, and easy control with a wide variation range. To verify the validity of the proposed scheme, simulations and experiments are carried out.